Optimization of NC-LSPR coupled MoS2 phototransistors for high-performance broad-spectrum detection

Abstract

In this work, negative-capacitance (NC) and local surface plasmon resonance (LSPR) coupled MoS2 phototransistors with a gate stack of HZO/AuNPs/Al2O3/MoS2 are fabricated, and the impacts of Al2O3 interlayer-thickness (T AlO) on the LSPR effect, the tensile strain on MoS2 from the Au nanoparticles (AuNPs), the capacitance matching of the NC effect from Hf0.5Zr0.5O2 (HZO) ferroelectric layer and the optoelectrical properties of the relevant devices are investigated. Through optimizing T AlO, excellent optoelectrical properties of phototransistors with a T AlO of 3 nm are achieved: a subthreshold swing (SS) of 25.76 mV/dec and ultrahigh detectivity of over 1014 Jones under 740 nm illumination. This is primarily because the NC-LSPR coupled structure can achieve an ultra-low SS through capacitance matching and a good interface passivation through optimizing Al2O3 interlayer to maintain effective LSPR and strain effects cross the MoS2 to enhance optical absorption and detection range. This work provides a comprehensive analysis on effective distance range of the non-direct-contacted LSPR effect and its combination with capacitance matching of NC effect, culminating in an optimized NC-LSPR coupled MoS2 phototransistor with a good consistency across an array of 30 devices, and offering a viable solution for the preparation of large-area, high-performance and broad-spectrum response 2D phototransistor array.